Telephone-exchange system



March 2 1926.

w. c. WEAVER TELEPHONE EXCHANGE SYSTEM March 2 ,.1926. 2 1,575,299 W. C. WEAVER I TELEPHONE AEXCHANGE SYSTEM Filed Oct. 29, 1923 3 Sheets-Sheva#l 2 BDIIUUDD DIHI I] March 2, 1926.

w. c, WEAVER TELEPHONE EXC'HANGE sYsTun Filed oct. 29, 192: s sheets-sheet 5 Patented Mar. 2, 1926.

Unirse srar earner ermee.

WiLLrAM c. Wnavnn, on naar cannon, new Jnnsn'r, Assrenon To WESTERN ELEC- TRIC COMPANY, INCORPORATED, l? NETN YORK; N.

YORK.

A CORPORATION or NEW 'lELEPHGHTHXCHANGE SYSTEM,

AAanleation filed @stehe-r 59, 1925 Serial No. 671361'.

lxchaugre Systems, ot which the following' is a full, clear, concise, and exact description,

This invention relates to telephone ex change systems and more particularly to systems involving;` the use of machine switchinra apparatus for the establishment ot con? nections.

In exchange systems of the above mentioned character it is desirable to enable con nections to be established from distant toll points to any subscribers line in the exchange area over the automatic switching mechanism of the exchange. Two methods ot' establishing such connections may be employed, depending upon the nature ofthe equipment at the toll point. It the toll point is equipped entirely with manual 'apparatus, a connection may rst be obtained over a toll line with the Vtoll switching' operator who may then, by means of key indicator equipment, select an idle trunk extending to the oitice ot the exchange in which the wanted line terminates and under the control of the key indicator sender complete the. .connection over the selected trunk by ineans ot selector switches. It the toll point is another exchange area ot the machine switching' character, the connection with the wanted line ma;T be established entirely by automatic selector switches under the control et such distant toll operator. ln either case it is desirable to enable the toll operator who is responsible for the establishn'ient of the connection to be able to initiate the application oit ringing current to the wanted line and in the event of a connectiou to a private branch exchange line to 1ro-ring' the operator at such brauch exchange when occasion arises. I

.lt is, therefore, an object ot the invention to enable toll calls originating Vat distant toll points to be completed to the lines of subscribers in a machine switchingjarea by means et selector switches and to permit the toll operator to control the application ot rii'lrfinp; current to thepwanted line. i

ore particularly, it is an object of the invention to Vprovide means at an incoming toll selector under` the control cfa distant toll 'operator ior initiating the automatic application of ringing current toa wanted line, the ringing current :being cut-oliE upon the response of' the called subscriber, and, it the wanted line is a private' branch `exchange line, ior rer-inging the private branch op* erster, the ringing` current being applied and cut-oil' at the will ofthe toll operator.

A feature of the invention is the provision, in a selector circuit,` of a ringing relug7 vhich, when initially operated under the control of ringingcurrent applied to the incoming end et the circuit, is locked inan operated condition and applies ringing current to the outgoing end et the circuit until the called subscribery or private branch exchange operator responds.f Ifthe call` is ter-l minated on a private branch exchange line, circuit changes are etl'ected whereby the ringing relay is rendered responsiveto each application ot ringing current to the incoming7 end oig' the circuit tor the purpose of lreringing` the private branch exchange 0perator. Y Y

This `and other features contemplated in the present invention will become more clearly understood from a consideration ot the a'ccompanying,-V drawings and the appended claims. Y l

' Referring to the drawings, Fig. `l shows at the right `a trunk circuit outgoing to a t'ull mechanical otiice of an exchange area and accessible from a toll point shown in the upper le't portion ot the figure, or, troni a toll point ot' a different character vas shown in the lower lettportion ot the igure. lu the lower right corner ofthe ligure, a key indicator link is diagrammatically illustrated. toll operator whose position is shown inthe upper lett portion et the ligure.

Fig; shows an incomingl selector ,circuit in which the'trunl; circuit ot Fig. l terminates, together with the control circuits thereof, and ringing" control apparat-us enibodjving tho present invention. Y

3 shows a final selector switch acces* sible from the incoming'r selector switch of Fig. 2 together with the control circuits thereof, a multi-station'subscriber-ts line terminating; therein, and a private branch ex change line termirmting at auV operators polrlhis link is under the control of the i calls initiated thereby, it would, in practice,

be associated with the usual recording operators position and calls would be handled thereto in accordance with the standard toll practice. In order to simplify the disclosure, however, only the toll switching op erators position O has been disclosed andv it will be assumed herein that the toll Voperator makes direct connection with the calling line. The toll point atwhich the operators position O is located is provided with key indicator mechanism diagrammatica-lly disclosed in the broken line rectangle in the lower right corner of Fig. 1.A This key indicator mechanism may be of the general type' disclosed in the patent to L. M. Allen, No. 1,513,362 issued Got. 28, 1924. This key indicator mechanism comprises a plurality of office senders, a keyboard for each toll operators position and a plurality of links for associating keyboards, senders and outgoing trunks with each other. Each link circult is provided with a plurality of trunk selecting switches for selecting an idle trunk from the groups extending to the several oflices of the exchange, arsender selector for associating an idle sender with the Vselected outgoing trunk and an operators position finder for associating the selected sender with the keyboard of the toll operators position. y

The tell 1ine174 and toll district selector 175 shown in the lower left portion of Fig. 1 are employed for establishing toll connections Yfrom a distant toll Vpoint of a me` chanical switching area and may be of the general type disclosed in the application of l/V. C. Jordan, Serial No. 680,807, filed ec. 15, 1923.

The selector switches shown in Figs. 2 and 3 are of the well known revertive impulse power driven type and may be in general the same as lthe switch described in the patent to E. B. Craft and J. N. Reynolds, No. 1,123,696, issued January 5, 1915.

It is thought that the invention will be best understood from a detailed description of the manner in which toll connections may be established. It will first be assumedthat the calling subscriber A desires to establish a toll connection with the party line shown in Fig.' 3 and with the substation B thereof, this connection Vbeing established through the toll operators position O. Assume that the toll operator has received the information regarding the desired toll call, this in formation including the number of the calling subscribers line, the name of the ollico containing such line, the name of the oliicc containing thewanted subscribers line and the number of such line. 'Having learned -the naine of the oliice and the number of the `who is initiating a call; and to select an idle trunk from the group of trunks extending to the oiiice -fin which the desired line is located. p j

After trunk selector 150 has selected an idle trunk from the group, it Vbeing' assumed that the trunk 118, 119 is idle and is selected,'a visual indication of the identity of the selected trunk is displayed before the operator in the usual manner in order that she may know which one of the total number of trunks she is to employ in making the connection. Observing the indication of the trunk selected, the operator inserts the plug 116of a holding cord circuit 115 in the jack 117 of such trunk. Holding cord 115 is for the purpose of maintaining the set condition of-vswitches which later establish the connection from the trunk 118, 119 to the `wa-nted subscribers line in order that such line may not be seized by other switches andy made busy while the toll operator is completing the connection. rlhe insertion of the plug 116 in the Vjack of the selected trunk completes a circuit from battery over the sleeve of said plug and jack, conductor 120 and winding of relay 108 to ground. ground potential at its inner left armature to conductor llaand the multiples of terminal 127 in other trunk selector switches similar to the switch to render such trunk non-selectable. In addition, ground potential is applied tothe multiples of terminal 111 appearing in all lthe district selee tor switches similar to to prevent the trunk from being seized by toll district selectors under the control of toll lines, such as 174. After the register sender has taken .itscompletesetting in accordance with the designation of the wanted subscribers line, the fundamental vcircuit is completed lfor controlling the brush selecting operation of the incoming selector switch shown in Fig. 2. This circuit may be traced in part from battery, through the left winding of relay 205, the upper contacts of cam 209, Ythe low-er right contact of cam 215, the upper Relayy 108 operates connecting ttl) amazon lett contant :oiteain 200, conductor 235,v eondut-tor 230, vllorush 125'tl'1enee"through lthe steppingrelay 128andaseoeiated circuits ot thehey indicatoreender,` brush12b, conductors 231 and 236 to ,ground throng-h the :lower contacts of ean'i`l`207. Relays l28jand `205 Aenergize in the ltundainental `circuit.

"Relay 205 completes aeoireuittron'i ground 4at its right 4armature `and Yfront sont-laat through thc-:lower lei-t eontact ot Cani 212 to "battery through the Ninagnet winding oi' eewpuenee switehn210 vfor advancing the. -sequenee switelr out ot position 1 and-into position12 wherea eireuit is elosed'tor the 'up-'drive Apowermagnet 218. This circuit .maybe i traeed 'from :battery l.through the `winding.of magnet 218,'the lower right eontaet. olt'veain212 io-ground at the rightftront Contact ot relay 205. lnposition 2 koifthe `sequence switeh, `relay 205 is maintained energized `in -a i oireuit Atroni battery n' through *its le't'ti'ront `,Contact andthe lower right eontaetiotcain 215 thence `over the funda* knientai eireuit to ground as described.

"The updrive `magnet `2118 Causes the brushes oi' the selector to inlove upfwalidly and tor Aeach brush tripping position passed over, a eireuit is 'closed as tollowstor shuntinpgout thestepping relay 128, maintaining the relay 4205 operated: battery7 throughsthe lett uwinding` and lett `trent oontactot relay l205,lower.cont-acts ot cani '215, eonnnutator 230, brush 228 to -lground at the lower lett `commet ofeani 213. The ste) ninvvrela 128` i :n Y

is deenergized each time theUabovefftraeed f'hunt- Circuitv is closed yandV the register eender operatesto `determine the `amount yof `movement iinpar'ted to the switch. Mhen the proper' lset iof brushes is reached, Ithe sender `opens thel'fliundaniental circuit .inl the il manner and as soon thereafter .asthe l'rlrush 228 Vengages `an insulated segment on eoininutator 230, the relay'205 retracts its armaturesand opens the ,circuit .of the .up- -drivepower magnet 218; Relay 205 :also closes .a circuit 'from ground, through. .its

r1 it back Contact, flower lettFContaet' of nin 2151to battery throughfthe 1winding of eequenee switch '210 driving said sequence switch out ot position 2fand intoposition .3.

ln position I?) ot-sequenoe'switeh 210,the Fundamental circuit; is Vagain closed :in the manner i above described-and `relayr205 :again energieinr elosesfthe previously ztnaeefd 4:oir-

cuitover its riahtfiiront Contact torednano i .ing-seipienee switehz210 intofiposition ft. In :position rele-.y `205 preniaine @energized and completes the circuit torzthe arp-drive ipower magnet :218i tor driving ithe switehfshaft Vupwardly `in' its group selecting movement. The tripping.; @nag-net l219 `energizes `in 1fposition' et sequence switehl210-overareireuit closechat the `lower contaets-ot1canr2l1t and ipositions the :tripiiing-.spindle ot the switch group Aiseleetii-ig mioveinent of `the switch shaft the selected set ot brushes is tripped to encounter thefn'iu-ltiple terminals otf zthe bank. For eaehgroup roit terminals trav ersedbyrfthe tripped set otvbrushes, ra eircuit -isfelosedrom battery, through the lett `winehing andelettltrontoontaet o't relay 20o, `the-"-lower right-contact ot earn 215, `the up- .;perhrighteontaet ot @am 206, .eonnnutator l231;brush-227 to ground Vat'the lower lett `-contaet of @am 213. 1

"The Closure ot this circuit holds the re lay 205 energized :and shunts out the stepping relay 1528. ifflientlie register of the sender 1hasheeoine satisfied, the fundamental circuit is opened .and relay 205 .becomes deenergized, immediately that the brush 22? eneountthe next insililating segniient ot eolnrinutator `Relay 205 opens lthe cireuit ot'lthe poweil .magnet 218 and -eon'i 'ln position 5' oft `sequence switch 210,

circuit is Closed troni batterythi'ouggh the -ht winding Aof relay 205 to ground f rrough therig'ht Contacts otleain 2311. #Relay 205 operates and looks =in the following' circuit provided the tirst trunk in the`- fgronp upon the terrninalslof =whieh the #brushes 22:1, l222. and 2 1?) yare-now etaniilf lingiisbusyzbattery, through the lett wi'ndf ing and lett stront cont-act :ot relay "205, tupperfeontaets ot Gain 214e, brush 223 'to *the grounded testterminal i oit the busy 'ftrunln lelay205iat itsrip'ht iront Contact lo'losesia Circuit over the lower-lett Contact ot eani`12ll2lfor driving sequence switch v210 into position 16. i Relay 205 xreniains V.lenerfgizediinitlii.s`.pos'i.tion Aand eoinpletes a'err.- :ouitironrritsiright trent` Contact, the lowe;I fright oontactgofcanr2l2 `to `battery through lthe winding et upfdryive Ypower i'nagnet 218 .whereby Lthefibrush shaft is driven upwardlgv utonnove ,the brushes `221,1222 and 223 `over fthetenininals Yofthe ipjroup to hunt tor an .,idle'trunlr` line. ,"When the pfirst idle trunk `isart-znehed, no ground Ipotential rheingg pressent upon the testterminal,.the holdingleir- 4:euitfot :relay :205 is opened. This relay., however, nenni-ins energized :tor no .instant @by `n'ieansioi'wa Cireuiti'troin l: attery, through iii- .the right winding oft snijd relai/,Flower rie'ht :and` iroperetlett contacts ot cani 23311, com

'ilnutator 2&2, brushfB/lt), the kuppercontact ffoiizoainI/li tol grroundiattheiizight .trout oontact :of relay 205. Ilifhen Vthewln'ush .229 en- .fgagee-zlthe inert insulating segment" of coni- ,enntator` 232, .relay 205 is deenerpgized and the Circuit ot the11nagnet-218 l'swopened, causing `the brush :sh att. to Cease its aipward ianoveinent. @Relay 205,-at its right haelt oonztaetfelosesizifeiroui entendineioyer the .ower vfieiit .oontaet` of main: 2111 `ory iadvaneinpl Y sequence switch 210 out of position 6 into position 7.

In position 7 of sequence switch 210, a circuit is closed from battery, through the left winding of relay 205, upper contacts of cam 209, lower contact of cam 216, brush 222, trunk conductor 225upper left and lower right contacts of cam 305 to ground at the lower left contact of cam 306. Relay 205 becomes energized and closes a circuit through its right front` contact for driving .sequence switch 210 out of position 7 into position 8. lVhile sequence switch 210 is moving from position 7 to position 8, relay 205 is held energized over its left windingl aud left front contact, lower Contact of cam 216 to ground as traced.

The trunk2211, 225 selected by the incoming switch is held busy so as not to be selectable by other switches by means of ground potential placed on the test conductor YThis potential is applied from ground, through the right contacts of cam 21%, test brush 223 and thence to the multiple terniinals of the test conductor before all other switches.

The fundamental circuit for controlling the brush tripping movement of the final selector switch, shown in Fig. 3, is now completed and may be traced from battery, through the right winding of relay 300, the lower left contact of cam 303, the lower left contact of cam 302, conductor 224, brush 221, the right contact of cam 217, trunk conductor 235 thence as traced through the sender, returning over conductor 236, the

upper contact of cam 212 to ground at theright front contact of relay 205. Relay 300 energizes and closes a circuit for relay 321 which may be traced from battery,through the left winding of this relay, upper left contact of cam 307, left front contact of relay 300 to ground at the upper contact of cam 308. Relay 321 energizes in this circuit and at its left front contact closes a locking ci-rcuit for itself extending from battery, through its left winding, back contact of relay 324, left front contact of relay 321 to ground on conductor 226. Relay 321,7upon energizing, closes a circuit extending from ground, at its right front contact over the lower contacts of cam 309 to battery through the magnet winding of sequence switch 310 for advancing sequence switch 310 into position 2. When sequence switch 310 moves out. of position 1, the initial energizing circuit of relay 300 is opened at the lower contact of cam 303, the relay 300 remaining energized over the fundamental .the fundamental circuit by reason of a locking circuit eX- tending from battery, throughv its right winding, lower contact of cam 340, the right front contact of relay 300, the lower right contact of cam 303 thence to ground over circuit as previously traced. Relay 300, upon energizing, and with sequence switch 310 in position 2, closes a circuit for the lhigh speed up-drive magnet 326 extending from battery, through the winding of magnet 326, the upper right contact of cam 311, the left front contact` of relay 300 to ground at the upper contact of cam 308. Magnet 326, upon energizing, advances the switch shaft of the final selector in its brush selection movement. As the switch shaft approaches each brush selection position, the brush 336 engages a conducting portion of commutator 330, thereby establishing a shunt around the winding ofthe stepping relay of the sender, maintaining relay 300 energized. This shunt circuit-'may be traced from battery, through the right winding of relay 300, the lower contact of cam 34.0, the right front contact of relay 300, the lower'right contact of cam 303, the upper right contact of cam 302,

Lcommutator 330, brush 336, the right contact of cam 307, the left front contact of relay 300 to ground at the upper contact of cam 308. As soon as the sender register is satisfied, the fundamental circuit is opened atvthe sender and as soon thereafter as brush 336 engages the next insulating portion of commutator 330, the holding circuit of re- -lay 300 is opened and relay 300 deenergizes.

As soon as relay 300 retracts its armatures, the circuit of the rip-drive magnet 326 is opened and a circuit is established from groundat the upper contact of cam 308, the

left back contact of relay 300, the lower right contact of cam 312 to battery through the magnet winding of sequence switch 310, for advancing the sequence switch 310 into position 3. lilith the sequence switch in position 3 a circuit-is closedfrom ground at the lower right contact of cam 306 through the winding of tripping magnet 335 for rotating the tripping spindle preparatory to tripping the selected set of brushes.

When sequence switch 310 vreaches posiv `tion 3, the energizing circuit yof relay 300 and thestepping relay 128 of the sender is again established. -Relay 300 again establishes the previously traced circuit for ad- "vancing sequence switch 310 out of position 31 into position 4; In positon 1, the circuit of the up-drivemagnet 326 is again established as previously traced for advancing the switch shaft in its group or ktens selection movement. During-the initial portion of this movement, the selected set of brushes is tripped in the well known manner. As the switch shaft approaches its first group selection position, the brush 338 engages the lowermost conducting portion of commutator 337 and a circuit is closed in shunt of the stepping relay of the .sender and may be traced from battery, through the right winding of relay 300, the lower contact of cam 34,0, the right front Contact of relayV los llO

300, the right' contziets.v .of @am 3035 commutetor 30?., bruslil 838i incl` thence` ae tracedy to f gfrouncle` nti theuppen Contact i of Cami 308;A

i-Mstlieswitch slieftl advances, .the sender' gages tlie-` next .insuleting;` portion, of the eominutetor 337, rel-ey 300 cleenergizes. opening, the eireu-ie. ot heupdrive magnet- 326f and. closing! thef previously traced Cineuit over tlieloiver riglit Contact; oli. eem; 312 for ziclvenemgsequenee switch 310111130` positioir.. I l

.in izsoeition :,tlie fundamenta-.l1.circuit 1e 0. With rele-.y 300 energized and sequence switelr 310 in position 0,? a; @militie-establielied for? tliex low speed. upedrlve power;

nia: et extending: from buttery, through. 1, r' the itlingg, oitliis magnet, the low er leit conteot of @ein 3071, the leitti roiitconteet ofi relay $00- to.- ;ground at' the' upper. eonteetrof eem. lfiegnet 339;.upon.- energizing, ecl-` veneestlie switch sliitfti inits lunitsi seleetione movement. During' this upward; moveii'ientA ol'. tlie` Switch. slieii't` enicinteirinittent.shunt circuit is estnlilisllerli whichi may be' traoefl troni buttery., flirougln tliey loft. vif'iuelingoirelay 300` the-lower eontnetoi.A @ein 3-105ftlie` if [lit liront Contact of 1..elfiy:300,` tlie'lower rig/lit eontizet of CenoV 308g. tlieupoer: right. Contact. of eem: 302, ooniiiiutetorf 3130, brush 3330., tlienee` ee'eti'eeecl f tot ground.- at itlie upper Contact of eeinBOSi Relay 300 is .inaintaineil enc tiizeil initliie `shunt.Circuit but the sender: stepping," relay is*interniitently` deene'rgized until the sentier i'egieterfis setistiecl'twlien the' fundzimen tel' circuit is opened; et tli'ef eenden. iiseoon tlieifeafteii as the'ljrusli oi-engteges" the nent insulating" portion'. ol eoniinutatorf 330, roloyi 300A retreetss its' arineturem, openm ing; the eirenitoftlie 'upfdrive-finegnet 3395 enel eloeinge; the previously-treeeclcircuit for" driving; the Sequence ewiteli 31.0"outo'lI posirr tion@ zinelfinto'positioni);

The l'ruelies :tn-lf SL12 "here now. lileenf. poi'eitioneel uponrtlie terminales the; desired lino and` the final selector sW-itclii tlieieuponii proeeedeI inf tlie; usuali inzinnery to' test1 the line or'its busy; oi idle condition.` iliseuinino" tliat the minted line; ie found to` be idle', `the sequence switch 310 is.-l adveneedf through intermediate positions from posi-` tion 9 into tlietalkinpjposition15; inrwliiclia poeitiontlie talking; circuit" roinf conductorsf enfl eonmeteV ot' com 302 andi tlieunperi contacts ofi eem. 305; brushes 352:' ancl to tlie con aluetore oi?. the called". linef. Y

li'llien sequence switeli310 lezwesposition et@ tlie circuit lieieinloeore traeetliforfrelay o iewopened. it tlie lower' lell't Contact of fi-ini. established.` :1n-cl relayv 300y enengz-izee',-.` et if'eneingi sfequeneefswiteli 31'01ntofpos1t1on is esteblislied overv tlie lower' eem .306` :incl nel ayf205 thereupon.deenergizesfy Relay 20o, upon deenergizino;,eloses .ai ein euit` from grounch. at its rigl1it. bacle. oontefet over tlie=lower le'lftonfteet.o-tioam-l foe zielwinein` seoliienney switeli. 21.0. out i off Dosis tion S- tifndf-into position-9.1 iVitl'Lseqi-ienee sw-itelr 2.120 .in `position` 9,..i'eliiy 205. is. (3011.-. neetetlf ine, eii'euiteiitendint.- to the .key indieeten` senden Wliieli` may legtroeecll from. battery, through the# left Winding;V of. relay?` 205.tne iii.ggli.t.eolitaets cat-'foam 209, Conduce toi^e236f` enel 2312 and. tlienee through.. ther sender, v ie'tufi'nin erven eoncluetonsi 230.. aan df` the: upper lett eonteet olf.. @ein 20.6.'to, ground! at: tlie` iuoper` leftonteet oateain,2115;A

Relay 205` `eneiigaizes' in thisA circuiti-enclet its ri d 1 front. eonteetloses at iieuit for ect` veneingzsequenee switelt` 21.0.fr`01n position: 9A intoposition 11i.. frs zthe Asequeneeswiteln is` peesingzroin. posizt-i'onf into position 1.1,.re.` leyy 2317 isieneligizediover the lower Contact` ing; of relay:t 109; right. fronti Contact of .reley 108q.ie'ondiietoi"V 1241.; .bnusli 1231 and: tlienee i to ground Relay 1091o1oe11atesen'fl4 locke 4in@ :i Circuit extending from ground',` through.

itsr left izvindingVY and left.` front Contact?y resietnnee-i elements` melf 106'1t0battery.-` iet. itsright eoet'eetyreley 109 estetolisieS-.enz` obiiiouseireuit. for relay- 110f. Wfliieli eoin= pletee.; the:` eouneietfion: roinx eon'duetorsy 1.185 enel: 11.91 to titunle .cond'uetors.-235 anel236; respectively: Atlv its lcmfermoet1` front eem;` tnet, relry 1-10/eppl-iesfg1ound potentiel; to.` conductor: 114 and1 o tliewmultiples of'i'teii-fininel.. 1.2.7 for rendering` the'. trunku non'.-k

, selectable: ln: addition? relay.` l110` atmits lower f front. Contact connects k' gfiiounel tozeonfiluetor 238" whereupon' an ei-'rouibf is esteb-- lished: over tliefeoutaot ofi `eem 208, tlieloweit left and upper rig'liteontztets of eef-1111209 betteny tliroufgli the left"y Wintlingif oil relen 20.5: `Relay 205- thereupon` energize-2.:` elosiiv weireuitvv over itseriglitvfionteconteetfuid t lower left eontaet: of'loeinf 2.12fand tobiut-teiy i through: eequeneeswite'h" nieguen 210. for ede Wuming.- tlie: i sequence: switelii frontiV position-.` 11 int'omositionv 13; frsfsoonxesltliesequenee switch `leavesposition i 11, .relay 237?" dee-nere 2grizes, After sequencefswitelr 210fleavesfpo-f Siteionf11-,u reley 205is-i1neinteinedfj'loliedi toi ground .ouy conductor 2138;,0Ven its1li-:ift=wii1fl-sl ing and left-ai'ontzeonteetu andi the left' eeneA teets of'. eziinr200l` 'Eherswitches-remain. iny

lge

this -condition until the toll operator initiates the ringing functions.

The toll operator, by means of the plug 104, establishes connection with the jack 103 and thence in the well known manner with the calling line A and to'complete the toll connection to the called subscribers line vwithdraws the plug 116 from the jack 117 and inserts the plug 112 in place thereof` As soon as the plug 116 is withdrawn from the jack 117, relay 108 deenergizes and closes a circuit for relay 107 extending from battery, through the winding of this relay, uppermost front contact of relay 110, outer left backcontact of relay 108,'the inner-normal contacts of relay 107 to ground at the common timing device as indicated. Relay 107thereupon energizes, locking itself directly to ground at the front contact of its inner armature. At its outermost armature contact, relay 107 closes a starting circuit for the timing device which, after a time interval in the manner fully set forth in the patent to F. J. Scudder, No. 1,517,257, issued Dec. 2, 1924, establishes a circuit for releasing relay 109if the operator fails to insert the plug 112in the jack 117 within a predetermined period. Assuming that the operator changes plugs quickly, relay 108 again energizes over conductor 120 and the sleeves of jack 117 and plug- 112 to battery through the winding of relay 113 before the timing circuit has completed its function and consequently relay 107 is released at the outer left back contact of relay 108 before the timing circuit functions to shunt down relay 109.

wWith the plug 112 in the jack 107, the operators cord circuit is connected with the trunk 235,236 and the completed connection is in condition for the ringing operation. Relay 113 bridges supervisory relay 100 across the strands of the cord circuit whereupon relay 100 operates to light lamp 101 as a ringing signal. The circuit of relay 100 extends from battery right winding of coil 200 outer right back'contactof relay 201, lower left winding of repeating coil 239, upper contacts of cam 207 conductors 236, 119, ring contacts of jack 117 and plug 112, front contact of relay 113, winding of relay 100, tip contacts of plug 112 and jack 117, conductors 118 and 235, lower contacts of cam 206, upper left winding .of repeating coil 239, inner contact of relay 201, left winding of coil 200, to ground at the outer back contact of relay 237. To initiate ringing, the toll operator depresses the ringing key 121 thereby bridging 'the ringing source 122 across the tip and ring strands of the cord circuit. Current thereupon flows from source 122 over the lower alternate Contact of key 121, ring contacts of plug 112 and jack 117, conductor 119, conductor 236, the upper contacts of cam 207, the lower left winding of. repeating coil 239, condenser 240, relay 202, the upper left winding of repeatingv coil 239, lower contacts of cani 206, conductors 235 and 118, tip contacts of jack 117 and plug 112 to ground at the upper alternatecontact of key 121. Relay 202 responds to the ringing current and estab' lishes' acircuit for relay 242 which may be traced from ground, inner back contact ot relay237, 'contact of relay202, back contact of' relay 262, innerileft normal contacts of: relay 242 to battery at the innermost lower back contact of relay 204. Relay 202 also closes a parallel circuitthrough the right Winding of relay 201 which' upon attract-ing,r its armatures, removes the windings of coil 200fro1n across the incoming end of the trunk circuit l235, 236 thereby extinguishing the lamp 101.

Relay 242 energizes in the circuit pre` viously traced, locking .itself directly to ground at its inner left front contact, shortcircuits the lower right winding of repeating coil 239 through its outer left front con-- tact and at its rightffront contact establishes a circuit for pick-up relay 244. This circuitL may be traced from battery through the winding and inner left normal contacts of relay 244, right front Contact of relay 242 to ground through the right contacts of cani 243. Relay 244 upon energizing locks over its inner left frontcontact, the back contact of relay 245, to ground at the inner back contact of relay 237 and also establishes a circuit from ground at its outer left contact to battery` through the winding of ringing relay 204. Relay 204 upon energizing in this circuit closes a circuit for alternate ly applying ringing current from the source 249 and battery to the called line. This cir cuit maybe traced from the ringing source 249, through the interrupter 248 or battery through the interrupter 247, through the right contactof cam 246, ringing cut-off relay 245, inner right front contact of relay 244, lower front contact of relay 204, upper contact of cam 216, brush 222, conductor 225, upper contacts of cam 305, brush 353, ring side of the called line to ground through the bell 314 of station B and to 'ground through the bell 313 of the other substation whose bell is connected to the same side ol' the line. Through the operation of interrupters 247 and 248, the bells 313 and 314 are operated in accordance with a one-ring" code. During the application of ringing current, ringing relay 204 connects ground over its innermost upper front contact, the. upper left contact of cam 217, brush 221, conductor 224, lower contacts of cam 302, brush 352 and thence to the tip side of the called line for shunting out the bells 316 and 317 of the other two substations to prevent theirl operation.

Assuming that the subscriber at substation isc Llll

is established for cutting' off the ringing current as soon as the interrupter 21'? reaches a. position in which direct'battery current is connected in the ringing circuit; In response to the reinoval ot the called partys receiver, relay 245 responds,opening'atlts armature and back contact the locking cir# cuit ot relay 244i. Relay 2&4 thereupon deenergizes, opening the circuit o't relay 2041 which disconnects the source off' ringingcur` rent and connects the called line through to the right' windings ot the repeating coil 239. As soon as the operator .releases the ringing lie y `following the initiation ottringing, relay 202 releases, releasing relay 201, whichagain establishes the circuit of relay tofflight lainp 101.

As soon as the called line isconnected' through to the repeating coil 230, is established. iorsupervisory relay 203, ex# tending troni battery, throughv theylower winding oit relay 203, the lowerright winding ot repeating coil239, the lowerinost baclr contact ol relay 204, thence as previously traced to the ring side of" the calledfline, through the substation B returning'over the tip side ofthe line to the left Contact: of

cani 21T, thence through the innevrniostupper baclrcontact of" relay` 204, the uppery right winding ot' repeating coil 239 to ground through the upper winding oit relay Relay 203 energizes, closingan obvious 203. circuit through the lett winding of relay 201 which again disconnects the windings et battery feed coil 200 :troni the left windings of repeating coil 239.' Relay 202'0per'- ates at this time but is without function., With coil 200disconnected, no circuit et# tective over the trunk to the toll operator-s position for maintaining relay 100V energized. Relay 100 thereupon deenergizes and1 extinguishesthe lanip 101, thislainp' having been lightedthrough theoperation et relay 100 troni theV tiine the toll: operator'released the ringing lcy -l'following the initiation oit ringing, up to-the tirne the called party' responded. theitoll operator is apprisedot'the factxthat thecalled party liasanswered and thatl tall;- ing may then take place over the established connection shown in heavy lines between the subscribers stations. The operator may listen in on; the connection when necessary by connecting her headset 129 to the cord circuit `by depressing key 102.

Had a connection been desired. with at party on the calledline whose bell is shown at 313, thenthe incoming selector would' have been set to select a final selector in ka di'l terent group having access to thesanie'party line and consequently Vthe brush 228 would have been in engagement with coniniutator aV circuit lilith the lainp 101 eXtinguished from the jack 117, releasingirelay 103:V

250: Therefore, wlien sequence switch-210A reached position 13, relay 237 beconiesenergized over a circuit iroin battery through the winding ollrelay237, theupper lett contact otcain` 2111, lconunutator 250, brush 251, thence to ground at the lower lett" contactof" earn 213.y lTJithr-elay 3'7"energized, a circuit isl established iroin ground at its innerright rontfcontact, lower. right contact of :cain 211 to battery throughy the winding o1:V sequence switch; magnet: 210 for advancing sequenceY switch' K magnet" 210 y from; 'position 13 into position 15., As soon as sequence switch 210'reachesposition13%, relay 237` becomes deenergized; le ringing' signal is thereupon transmitted to the toll operator through the operation of supervisory relay 100'over thel circuit previously traced. Supervisory' relay100, upon energizing in this circuit, lights the 1a1npl101 to apprise the operator that she: may proceed toL ring; llihen' the operator operatesringing key 12.1', relay 202 operates as previously described, closing the circuit of relay 201 'oryextinguishngifthe'lanip 101, andt closing: the pre` viouslytraced circuit for relay 2-2i Relay 2er-2 energiees''and` in' turn causes the operar, tion of' relays 21A` andf204. however, relay 244- energiaesover the" upper contacts of carri` 24T-1f t'o `ground"through in# ter "upter 250. Ringing `current"` andbattery are now applied totthe. called line'o'ver-tlie circuit previously ,traced but through the interrupters 253 and 252 andthe lett contactV off cam 24,6." Tllebellsand 314 are now operatedin` accordance with atwo-ring code.V Theresponseoithe calle'dparty results, as before" described, in the cutting'ot of the ringingcurrent, thel` operation or" re` lay 203, andthe'extinguishing of the lainp 101 toA indicate the response ol the calledl party. Y i

The ringingogttheothertwo parties ot. the party line, thebellsl' and' 317 o"l""whicli` are shown,is accomplished: inthe above de# 1n thiscase sie'i scribed manner but with diiilerentlsettings` of the' tina-lt selector brushes.

Vhen" the conversation is terminated and' the calledlparty restlore's'liis receiver tothe switchhoolr, relay 203P deenergizes"opening the` circuit of relay 201 which connects the windings ofcoil 200 in series with the4 left windings of: repeating' coill 239; i The `cir` cuit olii supervisory relay 100 at the toll board is new established, as betere described, and the lainp 101i is lighted to i nal the toll; operator that the*connection4 is no longerrequired; lnresponsetothis sigmnal", the tollfoperatorwithdraws the'plug 112 llelay` 108, uponreleasing, closesthe previously traced circuit' of relay 10T, which, through the timing; circuit, connects groundl potential? overthe` intermediate front contact oit relay 107 to the'juncti'on of resistance eleiso ments 105 and 106. Ground potential being now connected to both terminals ofthe left winding or' relay 109, relay 109 deenergizes opening the circuit or relay 110 which in turn removes busy groundV potential from the multiples or terminals 127 and 111 and opens the holding circuit of relay 205. Re-

lay 205 deenergizes and at, its right back contact closes a circuit for relay 237 extending from battery, through the winding of relay 237, the right contact of cam 241 to ground at the right back contact of relay 205. Relay 237, upon energizing, closes a circuit from ground at its inner right front contact over the lower right contact of cam 211 for advancing sequence switch .210 from either position, 13 or position 15' in which it is standing during lthe time the subscribers were conversing, into position 13.

As soon as the sequence switch 210 leaves position 1G, the circuit` of relay 237 is opened and relay 237 deenergizes. Vhen sequence switch 210 reaches position 1.8, a circuit is established for the down-drive magnet 220 extending 4from battery, through the winding of this magnet to ground over the lower contacts of cam 213. Magnet 220 drives the .switch shaft downwardly into its normal 'position where a circuit is established for advancing sequence switch 210 into its normal position. This circuit maybe traced from battery, through the winding of magnet 210, the upper right contact of cam 211, segment 233, brush 227 to ground at the lower lett contact of cam 213. All apparatus of the incoming selector is now in normal position. When the sequence switch 210 moved out of position 16, ground potential was removed at cam 214 from the brush 223, releasing relay 321. The release of the final selector then proceeds in the well known manner. v

The toll operator having released the mechanical equipment through'the removal of the plug 112 from jack 117 may entirely release her position apparatus by removing the plug 104 from jack 103. All apparatus employed in the establishment of the connection is now in normal condition and may be employed in the establishment ot other ringing current through the operation org ring-down relay 325. On such calls, however, the toll operator is enabled to re-ring the private branch exchange operator if it becomes necessary to call the operator in upon the established connection after she has once responded and her cord circuit is still connected to line 322, 323. Following the initial application of ringing current and the response of the operator, relay 203 is energized overthe windings of bridging coil 327 or' the branch exchange operators cord circuit and remains energized so long as the cord plug' isy in jack 331, and therefore relay 262 is energized over an obvious circuit extending through the contacts ot' cam 254 and the front contact or relay 203. l/Vhen, therefore, the toll operator again` throws the ringing key 121 for re-ringing the private branch exchange operator and relay 202 operates, a circuit is established 'from ground, through the inner right back contact of relay 4237, the 4iront contact or. relay 202, the armature and front contact of relay 262 to battery through the winding of ringing relay 204. Relay 204, there-k fore, energizes upon each depression ot the ringing key 121 and applies ringing current `from the source 255 through the inner right back contact of relay 244, the lower iront contact of relay 204, thence out over the' circuit previously traced, conductor 323, ring contacts of jack 331 and plug 332, through the ring-down relay 323 or the private branch exchange operators cord cir cuit, thence returning over the tip contacts of the plug and aclr to conductor 322 thence as previously traced'to ground at the innermost upper front'contact of relay 204. Relay 262 is held operated during the operation ot ringing relay 204 over a circuit extending from battery, through its winding the upper front contacts or relay 204 to ground at the outer right baclr contact of relay 244. Since the relay 204, is in this case, directly under 'the control of relay 202, ringing current is applied to the called line each time that the toll operator depresses her ringing key 121. The release or the established connection following the termination of talking proceeds in the Inan ner hereinbetore described and in accordance with the usual practice followed in establishingconnections to private branch ex" change.

Had the toll connection come from a toll point over the toll line 17 4 and over the htoll district selector 175, then the connection would havebeen extended to the incoming selector of Fig. 2, directly over conductors 230 and 231 from the terminal bank of the district selector 17 5. Following the seizure of the trunk conductors 235, 236 by the district selector 175, the distant toll operator then causes the setting` or the incoming selector ofFig. 2 and the final selector of Fig. 3 to connect with the wanted line. Following the complete extension or the toll connection to the terminals of the wanted line, the distanttoll operator proceeds to ring the wanted subscriber by depressing ner ringing lrey and causing the operation of ringing relay 17 2 at the district selector 175. The manner in which relay7 17 2 is controlled is fully set forth in the aforementioned application of W. C. Jordan, Serial No. 680,807, filed Dec. l5, 1923, and since it forms no material part of the invention is not fully disclosed herein. Relay li' upon energizing, applies currentfrom the source I7?, over the trunk line 235,236, causing the operation of relay 202. Ringing from the incoming selector through the operation of relay 2041-. then proceeds in the manner here inliefore set forth.

The invention claimed is:

1. In a telephone system, an incoming line, an outgoing line, a source of ringing current, a relay for applying said source to saidy outgoing line, means controlled over the incoming line for operating said relay, means controlled over said outgoing line for discontinuing the operation of said relay to disconnect said source of ringing current, and means operative thereafter for rendering said relay responsive to said first means to lapply and disconnect said source from said outgoing line at will.

2. In a telephone system, an incoming line, an outgoing line, a source of ringing current, a relay for applying' said source to said outgoing line, a second relay controlled over the vincoming line, for operating said first relay, means controlled over said outgoing line for discontinuing the operation of said first relay to disconnect said source of ringing current, and means operative thereafter for rendering said first relay responsive to said second relay to apply and disconnect said source from s-aid outgoing line at will.

3. In a telephone system, an incoming line, an outgoing line, a source of ringing current, a relay for applying said source to said outgoing line, a second source of ringing current, means for applying said second source to said incoming line, a relay in bridge of said incoming line responsive to said second source for operating said first relay, means controlled over said outgoing line for `discontinuing the operation of said first relay to disconnect said first source of ringing current, and means operative there-after for rendering said first relay responsive to said second relay to apply and disconnect said i'irst source from said outgoing line at will.

t. In a telephone system, an incoming line, an outgoing line, a source of ringing current,

a relay `for applying said source to said outgoing line, a second source of ringing current, manually controlled means for applying said second source to said incoming line, a relay in bridge of said incoming line responsive to said second source for oper-ating said lirst relay, means controlled over said outgoing line for discontinuing the operation of said first relay to disconnect said first source of ringing current, and means operative thereafter' for rendering said first relay responsive to said second relay to apply and disconnect said first source from said outgoing line in response to each operation of said manually controlled means.

5. In a telephone system, an incoming line, an outgoing line, a source of ringing current, a relay for applying said source to said outgoing line, a second source of ringing current, manually controlled means for applying said second source to said incoming line, a relay in bridge of said incoming line responsive to said second source for operating said .first relay, means controlled over said outgoing line for discontinuing the operation of said lirst relay to disconnect said first source of ringing current, a supervisory relay operable over said outgoing line, and means under the control of said supervisory relay for rendering said first rel-ay responsive to said second relay to apply and disconnect said lirst source from said outgoin line in response to each operation of said manually controlled means.

6. In a telephone system,a toll oper-ators position, a private branch exchange operators position, selector switches for extending a connection between said operators positions, a source of ringing current at one of said switches, a relay for applying said source over the established connection to said second operators position, means controlled from the first operators position for operating said relay, means operative following the response of the second operator for discontinuing the operation of said relay to disconnect said source of ringing current, and means operative from said second operators position for thereafter rendering said relay responsive to said first means to apply and disconnect said source at will'for recalling said second operator.

In witness whereof, I hereunto subscribe my name this v25th day of October D.,

WILLIAM C. WEAVER. 

